Image display system

ABSTRACT

An image display system capable of viewing an electronic image and an external sight simultaneously, or selectively is disclosed. The system comprises a plurality of image display units including a controller for outputting image signals and at least one display unit capable of enabling switching operation with a predetermined operation mode of a plurality of operation modes including a mode for indicating the image signals from the controller; an external control device for outputting mode control signals which address the operation mode of the display unit; the controller of the respective image display units being provided with an external control terminal for receiving the mode control signals and an output terminal for outputting the mode control signals supplied to the external control terminal; the outputs of different controllers are connected to the external control terminals thereof in turn so as to couple the plurality of controllers to the external control device in series, the remained control terminals are connected to the external control device, and the operation modes of whole display units are collectively and forcibly and/or individually controlled through the respective controllers on the basis of the mode control signals from the external control unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image display system capable ofviewing an electronic image and an external sight simultaneously, orselectively.

2. Related Art Statement

Hitherto, there has been provided a head mounted display (hereinafter,referred to as an HMD) having for example a see-through function capableof viewing not only an electronic image, but also an external sight (forexample, refer to Japanese Patent Application Opened Nos. 281,891/90 and26,289/92).

For example, Japanese Utility Model Application No. 52,288/94 disclosesan image display system in which a plurality of see-through HMDs can beconnected to a controller for outputting image signals, a third partyother than a viewer can control through the controller one operationmode which renders a given electronic image viewable to all viewers oran other operation mode which renders an external sight viewable to allviewers.

According to such an image display system, there is an advantageouseffect that for example, when applying the system as a service forpassengers on a passenger airplane, in the case of the taking-off andlanding of the airplane, a given electronic image such as "fasten seatbelt" can be forcibly viewed, or when applying education, it can berendered that all persons present at a lecture pay attention to ablackboard forcibly, or it can be rendered that all of them view anelectronic image of a given problem forcibly.

The present inventors found that there are points to be improved in theabove image display system. That is, in the above image display system,a plurality of HMDs are connected to only one controller, so that thenumber of HMDs are limited. The controller itself for controlling theimage signals also has a function for controlling the operation mode ofthe HMD forcibly from the outside, so that it is necessary to provide acircuit for generating such a forcible control signal in the controller.However, such forcible control circuits or the like are efficient in thecase of using a plurality of HMDs, but these circuits are not necessaryin the case of using only one HMD, so that in such only one HMDutilization, the system construction becomes uneconomical.

SUMMARY OF THE INVENTION

It is an object of the present invention to eliminate the abovedescribed disadvantages of the conventional image display system.

It is another object of the present invention to provide an imagedisplay system capable of adapting the number of the HMDs easily, andcapable of constructing the image display system economically in thecase of individual use.

According to the present invention, there is provided an image displaysystem comprising a plurality of image display units including acontroller for outputting image signals and at least one display meanscapable of enabling switching operation with a predetermined operationmode of a plurality of operation modes including a mode for indicatingthe image signals from the controller; an external control device foroutputting mode control signals which address the operation mode of thedisplay means; the controller of the respective image display unitsbeing provided with an external control terminal for receiving the modecontrol signals and an output terminal for outputting the mode controlsignals supplied to the external control terminal; the outputs ofdifferent controllers are connected to the external control terminalsthereof in turn so as to couple the plurality of controllers to theexternal control device in series, the remained control terminals areconnected to the external control device, and the operation modes ofwhole display means are collectively and forcibly and/or individuallycontrolled through the respective controllers on the basis of the modecontrol signals from the external control means.

According to the present invention, it is preferable to automaticallyswitch the control of the operation mode due to respective externalcontrol units themselves and collective control of the operation modedue to respective external control unit, in the point that the systemfurther comprises a detecting means for detecting whether the externalcontrol terminals of respective controllers are coupled to the externalcontrol device or not, and a priority order of a collective and forciblecontrol of the operation mode of display means corresponding to thecontroller due to the mode control signals from the external controldevice and an individual control of the operation mode of thecorresponding display device due to respective image display unitsthemselves is determined on the basis of the output of the detectingmeans.

In an embodiment of the image display system according to the presentinvention, it is preferable to optionally switch the collective controlof operation mode of whole display means due to respective image displayunit and the control of operation mode of the display meanscorresponding to the respective image display units themselves, in thepoint that the mode control signal from the external control deviceincludes a signal for addressing a priority order of a collectivecontrol of operation modes of display means by the external controldevice and an individual control of the operation mode of thecorresponding display device due to respective image display unitsthemselves.

According to the present invention, the plural operation modes includethe see-through operation mode. The external control device is formed bythe computer or the remote controller. The image display means comprisesimage display elements for displaying electronic image, an opticalsystem including a beam splitter for leading the electronic imagesdisplayed on the image display elements on eyes of the viewer, and ashutter means disposed at the opposite side to the eyes of the viewerfor the beam splitter, as well as the plural operation modes include thenormal mode for rendering the shutter means to shielding condition andfor displaying the electronic image on the image display elements; thesuperimposition mode for rendering the shutter means to transmittingcondition and for displaying the electronic image on the image displayelements; and the see-through mode for rendering the shutter means totransmitting condition and for not displaying the electronic image onthe image display elements.

In respective image display units of the present invention, thecontroller for outputting image signals and at least one display meanscapable of enabling switching operation with predetermined operationmode of operation modes including the mode for displaying image signalsfrom the controller are made a pair of elements, so that it is possibleto operate the display means with the predetermined operation mode inthe case of using a unit level. Moreover, respective controllers areprovided with an external control terminal for receiving the modecontrol signals and an output terminal for outputting the mode controlsignals supplied to the external control terminal, so that if theoutputs of different controllers are connected to the external controlterminal in turn so as to couple the plurality of controllers to theexternal control device in series, and the remained control terminalsare connected to the external control device, the external controlterminals of respective controllers may be coupled to the externalcontrol device in parallel. Therefore, the operation modes of wholedisplay means can be collectively controlled through the respectivecontrollers on the basis of the mode control signals from the externalcontrol means.

According to the present invention, the controller of the plural imagedisplay units each having the controller and at least one display meansis connected in series to one external control device through theexternal control terminal and the output terminal of respectivecontrollers, so that the external control device may controlcollectively and forcibly the operation modes of whole display meansthrough respective controllers, and thus may correspond easily to thenumber of the image display units, that is, the number of display means.Also, it is not necessary for the controller itself of respective imagedisplay units to have a function of forcibly controlling the operationmodes of the display means externally, so that the system constructionof respective image display units may be made cheap.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the construction of one embodimentof an image display unit used in embodiments of an image display systemaccording to the present invention;

FIG. 2 is an explanatory view showing the construction of one embodimentof a projection optical system of the HMD shown in FIG. 1;

FIG. 3 is an explanatory view explaining the switching order ofoperation modes of the HMD shown in FIG. 1;

FIG. 4 is an explanatory view showing the construction of a firstembodiment of the image display system according to the presentinvention;

FIG. 5 is an explanatory view explaining the construction for detectingpresence of a connection between a controller and a computer in thefirst embodiment of the image display system according to the presentinvention;

FIG. 6 is an explanatory view showing one embodiment of a mode switchingcontrol circuit shown in the first embodiment;

FIG. 7 is an explanatory view showing one embodiment of a mode switchingcontrol circuit shown in a second embodiment of the image display systemaccording to the present invention;

FIG. 8 is an explanatory view showing the construction of a thirdembodiment of the image display system according to the presentinvention;

FIG. 9 is an explanatory view showing the construction of a fourthembodiment of the image display system according to the presentinvention; and

FIG. 10 is an explanatory view showing the construction of a fifthembodiment of the image display system according to the presentinvention.

DETAILED EXPLANATION OF THE PREFERRED EMBODIMENTS

Now to the drawings, there are shown various embodiments of an imagedisplay system according to the present invention. Like parts are shownby corresponding reference characters throughout several views of thedrawings.

FIG. 1 is an perspective view showing a construction of one embodimentof an image display unit used in a first embodiment of an image displaysystem according to the present invention. The image display unit 10comprises an HMD 1 constructing at least one display means, a controller2 for controlling the operation modes of the HMD 1, and a cable 3 forconnecting these HMDs and the controller. The HMD 1 comprises right andleft projection optical systems 4a, 4b, right and left ear-phones 5a, 5band a switch 6 for switching the operation modes. The controller 2 alsocomprises circuits for supplying required power, image signal and voicesignals or the like to the HMD 1 through the cable 3, and a modeswitching unit. The controller 2 also included an external controlterminal for receiving mode control signals from an external controldevice described later and an output terminal for outputting the modecontrol signals inputted from the external control device. The HMD 1 orthe controller 2 is provided with a mode switching unit 6 provided onthe HMD 1 or a mode switching control circuit for controlling theoperation mode in the HMD 1 on the basis of the mode control signalsfrom the mode switching unit 6 provided on the controller 2 or of themode control signal from the external control device.

Each of right and left projection optical systems 4a, 4b comprises, forexample, as shown in FIG. 2, a liquid crystal element 11 (hereinafter,referred to as LCD), a half-mirror 12, a concave mirror 13 and a liquidcrystal shutter 14, and is constructed in such a manner that the imagedisplayed by the LCD 11 is transmitted through the half-mirror 12 andmagnified by the concave mirror 13 and then reflected on the half-mirror12 and observed by eyes 15 of the user and that the external field lightcan be led onto eyes 15 by transmitting it through the liquid crystalshutter 14 and the half-mirror 12.

In this embodiment, the LCD 11 of the HMD 1 and the liquid crystalshutter 14 are on/off-controlled by the mode switching control circuiton the basis of the mode switching signal, in such a manner that the HMD1 is selectively operated with three modes shown in Table 1, that is, anormal mode (N) for observing only the image displayed on the LCD 11, asuperimposition mode (SI) for observing a superimposed image of an imagedisplayed on the LCD 11 and an external field light, and a see-throughmode (ST) for observing only the external field light. In an individualuse of the image display unit 10, these modes are so controlled thatthey are switched for example in the order shown in FIG. 3 through themode switching control circuit, with every mode switching by theoperation of the mode switching unit 6 provided on the HMD 1 or the modeswitching unit (not shown) provided on the controller 2.

                  TABLE 1                                                         ______________________________________                                        Liquid Crystal Shutter                                                                       LCD          Operation Mode                                    ______________________________________                                        OFF            ON           Normal                                            (Light Shut-off)                                                                             (Image Display)                                                                            (N)                                               ON             ON           Superimposition                                   (Light Transmission)                                                                         OFF          (SI)                                              ON             (Dark-field) See-through                                                                   (ST)                                              ______________________________________                                    

FIG. 4 shows a construction of the image display system in a firstembodiment of the present invention. In this embodiment, a plurality ofimage display units 10-1, 10-2, 10-3, . . . , each having theconstruction shown in FIG. 1 is coupled to the computer 20 as anexternal control device, the operation modes of the HMDs 1-1, 1-2, 1-3,. . . , in respective image display units are collectively and forciblycontrolled through the corresponding controllers 2-1, 2-2, 2-3, . . . ,on the basis of the mode control signal of 2 bits from the computer 20.

To this end, in this embodiment, the external control terminal 21-1 ofthe controller 2-1 constituting the image display unit 10-1 is connectedto the computer 20 through a connector 22, and the output terminal 23-1of the controller 2-1 is connected to the external control terminal 21-2of the controller 2-2 constituting the image display unit 10-2. In thesame manner, the output terminals of different controllers are connectedto the external control terminals of another controller in order, insuch a manner that a plurality of controllers are coupled to theexternal control device 20 in series.

In this embodiment, also, the fact that the external control terminalsof respective controllers have been coupled to the computer 20, isdetected, and then the mode control due to the computer 20 is madepreferential. To this end, as shown in FIG. 5, respective externalcontrol terminals 21 are provided with two terminals 25-1, 25-2 forreceiving the mode control signal of two bits (S1, S2) from the computer20, and with two terminals 25-3, 25-4 for detecting the coupling of theexternal control terminal 21 to the computer 20 and for generating apriority order control signal (S3), the terminal 25-4 being grounded.The connector 22 connected to the computer 20 is provided with terminals26-1, 26-2 to be connected to the terminals 25-1, 25-2 of the externalcontrol terminal 21 and for supplying the mode control signals, andterminals 26-3, 26-4 to be connected to the terminals 25-3, 25-4, theterminals 26-3, 26-4 being short-circuited to each other.

In this way, as shown in Table 2, the priority order control signals S3having high level (H) in case of the external control terminal 21 notbeing connected to the connector 22, and having low level (L) in case ofthe external control terminal 21 being connected the connector 22, canbe obtained from the terminal 25-3 of the external control terminal 21,so that in the mode switching control circuit of respective imagedisplay units 10, it is possible to select whether the mode control isperformed by the mode switching unit provided on the HMD 1 or thecontroller 2 individually or by the computer 20 collectively andforcibly on the basis of the signal level conditions (H, L) of the thusobtained priority order control signals S3.

One embodiment of such a mode switching control circuit is shown in FIG.6. This mode switching control circuit 27 receives mode control signalsof two bits (S1, S2) supplied to the terminals 25-1, 25-2 of theexternal control terminal 21 from the computer 20, the priority ordercontrol signal (S3) generated by the coupling of the connector 22 to thethe external control terminal 21 and obtained from the terminal 25-3,and mode control signals of respective operation modes of normal (N),superimposition (SI) and see-through (ST) each obtained by the operationof the mode switching units 6 provided to the image display units 10themselves, so that the operation modes are controlled in order by themode control signals (N, ST, SI) obtained by the operation of the switchof the image display units 10 themselves in the case of the priorityorder control signal S3 being H level, and on the basis of the modecontrol signal of two bits from the computer 20 in the case of thepriority order control signal S3 being L level.

The mode control signals of two bits (S1, S2) outputted from thecomputer 20 are set by a combination of signal levels of respectivebits, for example, as shown in following Table 2.

                  TABLE 2                                                         ______________________________________                                        Signal Level                                                                  S1     S2    S3      Operation Mode                                                                             Control Mode                                ______________________________________                                        L      L             Normal (N)   Forcible and                                H      L     L       See-through (ST)                                                                           Collective                                  L      H             Superimposition (SI)                                                                       Control                                     H      H     H       (N), (ST), (SI)                                                                            Individual Control                          ______________________________________                                    

According to the embodiment of the present invention, the controllers2-1, 2-2, 2-3, . . . of an optional plurality of image display units10-1, 10-2, 10-3, . . . are coupled to one computer 20 in series throughthe external control terminals 21-1, 21-2, 21-3, . . . and outputterminals 23-1, 23-2, 23-3, . . . of respective controllers, so that theoperation modes of all HMDs 1-1, 1-2, 1-3, . . . can be collectively andforcibly controlled by the computer 20 through the respectivecontrollers, and thus can be corresponded to the number of the imagedisplay units 10, that is, the number of HMDs 1 easily.

In this embodiment, also, the operation modes can be directly addressedfrom the computer 20 so that in the single use of the image display unit10, even when the operation modes are switched in the order to normal,superimposition and see-through modes, every operation of the modeswitching unit, the operation modes can be switched from the normal modeto the see-through mode, immediately. Therefore, for example, for pluralunfamiliar viewers, the system that the see-through mode is setaccording to a certain curriculum, can be constructed. As in theconventional system, moreover, it is not necessary for the controllers 2themselves to have a function for controlling the operation modes of theHMD 1 forcibly from the outside, so that respective image display units10 can be constructed cheaply.

In a second embodiment of the image display system according to thepresent invention, for the construction of the image display systemshown in the first embodiment, it is optionally possible to select thecollective control of operation modes due to the computer 20 and theindividual control of operation modes due to the respective imagedisplay units 10, on the basis of the mode control signals from thecomputer 20, without detecting whether the external control terminals 21of respective controllers 2 are coupled to the computer 20 or not. Tothis end, in this embodiment, the connector 22 shown in FIG. 5 is notused, the external control terminals 21 of respective controllers 2 aredirectly connected to the computer 20, the mode control signals S1, S2having each signal level being H level are derived selectively from thecomputer 20 as a mode control signal of two bits, and as shown in FIG.7, these mode control signals are supplied to a mode switching controlcircuit 27 through the external control terminals 21 of respectivecontrollers 2.

The mode switching control circuit 27 also receives the mode controlsignals of respective operation modes of normal (N), superimposition(SI) and see-through (ST) each obtained by the operation of modeswitching units 6 provided on the corresponding image display units 10themselves, so that the mode control signals from the computer 20 areobserved in the mode switching control circuit 27. Therefore, if bothmode control signals of two bits (S1, S2) have a signal level of Hlevel, the mode control signals (N, ST, SI) obtained by the operation ofthe switch of the image display units themselves by the viewer have apriority, thereby individually and sequentially controlling theoperation modes, and if at least one of the mode control signals S1, S2has an L level, the mode control due to the computer 20 has a priority,thereby collectively and forcibly controlling the operation modesaccording to Table 2 on the basis of the mode control signals of twobits.

According to this embodiment, without detecting whether the externalcontrol terminals 21 of respective controllers 2 are coupled to thecomputer 20 or not, the collective and forcible control of the operationmodes of all HMDs 1 and the control of operation modes of thecorresponding HMDs 1 due to respective image display units 10 themselvescan optionally be switched, thereby obtaining an inexpensive systemconstruction. Moreover, under the state of coupling whole image displayunits 10 to the computer 20 in series, the priority order of the modecontrol due to the computer 20 and the mode control due to respectiveimage display units 10 themselves can be controlled, thereby increasingthe freedom of the system.

Therefore, for example, the operation mode may be switched to thesuperimposition mode and the see-through mode according to a curriculumor a software control, on the way of operation, for the plural imagedisplay units during operation at respective optional operation modes,so that it is possible to construct a system entering thesuperimposition mode at game-over, and entering the see-through modeforcibly under a urgent condition.

Moreover, a system for switching the image voice sources (supplysources) may be added by means of conventional ways. Commonly, aplurality of image voice sources may be connected to an controller ofthe image display unit through a selector to select the sources bychannels of the selector. By using this selector, for example, the modecontrol may be performed and the voice may be changed to another voicesource such as a microphone. Moreover, as a function of respective imagedisplay units, an automatic volume muting function may also be providedin such a manner that the sound volume level is automatically decreased.This means that the caution of the viewer may be directed to theexternal sight visually and audibly, irrespective of the condition ofthe voice source.

FIG. 8 shows a third embodiment of the present invention. Thisembodiment utilizes a remote controller 30 instead of the computer 20 asan external control device in the construction of the image displaysystems shown in the first and second embodiments. Therefore, accordingto this embodiment, it is possible to obtain the same effect as in thefirst and second embodiments. In this case, the remote controller 30generates the mode control signals of two bits (S1, S2) in the samemanner as the computer 20, so that the priority order for the modecontrol due to the remote controller 30 and the mode control due torespective image display units 10 themselves can be controlled in thesame manner as in the second embodiment.

FIG. 9 shows a fourth embodiment of the image display system accordingto the present invention. This embodiment has the same construction asthat of the third embodiment except that respective image displaysystems 10 comprise a plurality of HMDs 1 and one controller 2 forcontrolling HMDs commonly, with the transfer of signals between thecontroller 2 and the plural corresponding HMDs being performed by aradio system. Moreover, respective controllers 2 can supply differentmenus. Therefore, even in this embodiment, the priority order of themode control can be changed under an urgent condition to switch all HMDs1 to the see-through mode forcibly, in the same manner as in the secondand third embodiments.

FIG. 10 shows a fifth embodiment of the image display system accordingto the present invention. In this embodiment, a plurality of imagedisplay units 10 shown in FIG. 1 are coupled in series to form theplural (in this embodiment, two) image display unit groups 40-1, 40-2,these image display unit groups 40-1, 40-2 are connected to one computer20 in parallel, so that the computer 20 performs different mode controlbetween different image display unit groups and collective control inthe same image display unit group. In this embodiment, also, all HMDs 1may be switched forcibly and collectively to the see-through operationmode.

It is further understood by those skilled in the art that the presentinvention is not limited to only the above described embodiments andthat various changes and modifications may be made in the inventionwithout departing from the spirit and the scope thereof. For example, inthe first embodiment, the remote controller 30 can be used instead ofthe computer 20 in the same manner as in the third and fourthembodiments. In the fourth embodiment, also, the computer 20 is usedinstead of the remote controller 30, to detect whether the controller 2of respective image display units 10 is coupled to the computer 20 ornot in the same manner as in the first embodiment, thereby controllingthe priority order of the mode control due to the controller 20 and themode control due to respective image display units 10 themselves. In thefirst, second and third embodiments, moreover, the transfer of thesignals between the HMD 1 and the controller 2 of respective imagedisplay units 10 may be performed by the radio system in the same manneras in the fourth embodiment and in the fifth embodiment, respectiveimage display unit groups may be constructed by one or a plurality ofimage display units. In respective image display units 10, also, themode switching unit operated by the viewer may be provided to either oneof HMD 1 or the controller 2.

What is claimed is:
 1. An image display system comprising:(a) aplurality of image display units, each display unit comprising:(i) adisplay means for displaying image signals; (ii) an external controlterminal for receiving a mode control signal for causing a modeexchanging operation among a plurality of operation modes at the imagedisplay unit itself; (iii) a mode exchanging switch for specifying acondition of said mode control signal; (iv) a detection means fordetecting whether or not the external control terminal is connected to aconnector capable of outputting the mode control signal; (v) a modeexchanging control circuit for controlling the display means so as tocause a mode exchanging operation at the image display unit itself whenthe detection means detects connection of said external control terminalto the connector and for controlling the display means in accordancewith said condition of the mode control signal specified by the modeexchanging switch when the detection means detects non-connection ofsaid external control terminal to the connector; and (vi) an outputterminal for outputting the mode control signal input to said externalcontrol terminal; and (b) an external control device for outputting themode control signal to said external control terminal, the externalcontrol terminal of respective image display units being connected inseries to the output terminal of respective different image displayunits, and a particular one of said image display units in said serieshaving its external control terminal connected to the external controldevice; wherein:said plurality of image display units further comprisesat least two image display unit groups; each image display unit group ofsaid at least two image display unit groups has a separate connectionbetween an external control terminal of a particular one of said imagedisplay units and said external control device so that each imagedisplay unit group can operate in a mode that is independent of anyother of said image display unit groups.
 2. An image display system asclaimed in claim 1, wherein said plurality of operation modes include asee-through operation mode.
 3. An image display system as claimed inclaim 1, wherein said external control device comprises one of acomputer and a remote controller.
 4. An image display system as claimedin claim 1, wherein the image display units are head-mounted displayunits.
 5. An image display system as claimed in claim 1, wherein theplurality of operation modes of the image display means include a modefor operating a voice mute function.
 6. An image display system asclaimed in claim 1, wherein the display means comprises image displayelements for displaying an electronic image, an optical system includinga beam splitter for leading the electronic image displayed on the imagedisplay elements onto eyes of a viewer, and a shutter means disposed atthe opposite side to the eyes of the viewer from the beam splitter, andwherein the plurality of operation modes include (i) a normal mode forrendering the shutter means to shielding condition and for displayingthe electronic image on the image display elements, (ii) asuperimposition mode for rendering the shutter means to transmittingcondition and for displaying the electronic image on the image displayelements, and (iii) a see-through mode for rendering the shutter meansto transmitting condition and for not displaying the electronic image onthe image display elements.
 7. An image display system comprising aplurality of image display units, each display unit comprising:(a) adisplay means for displaying image signals; (b) an external controlterminal for receiving a mode control signal for mode exchanging at theimage display unit itself; (c) a mode exchanging switch for specifying acondition of said mode control signal; (d) a detection means fordetecting whether or not the external control terminal is connected to aconnector capable of outputting the mode control signal; (e) a modeexchanging control circuit for controlling the display means so as toexhibit the mode exchanging operation at the image display unit itselfwhen the detection means detects connection of said external controlterminal to the connector, and for controlling the display means inaccordance with said condition of the mode control signal specified bythe mode exchanging switch when the detection means detectsnon-connection of said external control terminal to the connecter; and(f) an output terminal for outputting the mode control signal inputtedto said external control terminal; whereinsaid detection means outputs apriority order control signal which becomes a high level (H) when saiddetection means detects said non-connection of the external controlterminal to the connector; said priority order control signal becomes alow level (L) when said detection means detects said connection of theexternal control terminal to the connector; and said mode exchangingcontrol circuit includes means for controlling the mode exchanging bydetermining whether the external control terminal is connected to theconnector, in accordance with said high level (H) or said low level (L)of the priority control signal.